Interest in the field of neural prosthetics has grown significantly in the last 20 years. Yet only few applications such as cochlear prosthesis have found their way into patient therapy. One of the major reasons for this lack of success is the interface between nerve and electrodes. Recent development in electrode design suggest that either reshaping the nerve into a flat configuration or maintaining the nerve in an already flat shape can improve the ability to interface with peripheral nerves. The Flat Nerve Interface Electrode (FINE) design is the result of research carried out during the last grant period. The central hypothesis of this proposal is that fascicular signals from peripheral nerves can be recovered and used to control the peripheral nervous system function with a multiple contact FINE cuff. This hypothesis will be tested with three specific aims: Aim 1: Signals from various fascicles within the nerve can be recovered, Aim 2: Neural activity within nerve can be controlled with multiple contact nerve electrodes, and Aim 3: Joint dynamics can be controlled by neural signals. The end product of this proposal will be a platform technology for closed-loop control of neural function that relies on a single approach for recording and stimulation with multicontact electrodes placed on peripheral nerves. The team assembled relies on expertise in various fields such as engineering, orthopedics and mathematics. This neurotechnology is applicable to many disorders of the nervous systems such as stroke, paralysis and autonomic nervous system disorders and to the control of artificial prosthetic limbs. In particular, peripheal nerve interfaces could provide a complementary approach to brain microelectrodes for the detection and control of neural function. 1